That log is from OBS Studio 0.16.6. I'd need to see a log from a current release of OBS. It's unlikely that anyone here is going to troubleshoot issues happening in any version of OBS that old, and I don't recall hearing of this particular issue. I didn't realize that you had only reproduced this issue on older versions and not the current version until I re-read this thread.
Using the OpenGL renderer on Windows also isn't really supported, as I've already sort of alluded to.
You should also be using the 64-bit OBS Studio on 64-bit Windows, unless you have a device that only works with 32-bit applications. I'm told that 32-bit OBS should be able to produce files larger 4GB (and it seemed to do so, in your case), though perhaps that is something to look into further.
This just means that you closed GTA5 after playing for 3 hours.
This just means that you closed StickFight after playing for 1.5 hours.
How are you verifying that your recordings are cut-off? Are you using a reliable media player? Are you using a 32-bit or 64-bit media player on files over 4GB?
If you ever reproduce this issue with a current release of OBS, then we can dig into it further.
So far I've been using my editing software in conjunction with VLC to verify my videos' integrity, and both crash once they reach the same point during video playback, becoming unresponsive until they are terminated and restarted.
The error log I sent is from the filming session where this issue occurred last. I had 16.6 installed due to the quirks of my previous PC, even if I understand why OpenGL has been removed since that version. I did not install anything more recent (the latest release) until afterward, realizing there had been an issue in recording. I honestly have no more information in that regard, other than the fact that OBS was still trying to render to a file that had been cut off, or perhaps the UI had glitched out slightly. The fact that OBS realized what was opened and closed when it truly was makes me think perhaps this is merely a compatibility issue with Windows and the older version of OBS, and that brings me back to the question I was origanlly here to get answered, whether or not OBS 21.1.2 will possibly perform the same. So far, after testing DirectX11 is running fine, and files up to 2gb have not been an issue, but it won't be for, most likely, another week and change before anything lasts long enough to reach 5gb.
(update)
Attached is a log file from the current version of OBS, where the same issue has occurred. The Application shows that encoding is proceeding fine, yet the file has been cut off before I stopped recording. This was during Bioshock 2 gameplay, so in the end I doubt it has anything to do with a lack of rescources.
Sorry if this counts as rambling.
Also, everything is 64bit except my editor (VSDC), which I believe is 32bit.
(Second update)
I've done a full reinstall of OBS and it seems that has done the trick. Maybe it was the extra preference files from the version 16.6 I had installed previously? I'm not totally sure. Either way, everything seems to be in order now. Thanks so much for you time and patience.